Originally, computers were rather elaborate constructions, the earliest of which took several rooms to house. Over time, the size of the computer was reduced dramatically, such that a computer capable of being placed on a desktop became commonplace.
Additional developments led to further reductions in the size of the computer, leading to computing devices having greater mobility and portability. In particular, a new type of portable computing device, commonly referred to as a laptop, was developed, together with a host of other portable computing devices, such as the Personal Digital Assistant (PDA), the mobile telephone and the like.
However, mobility and portability comes at a cost. Lacking a connection to an external power source, portable computing devices require an on-board power source, typically in form of one or more batteries. While such batteries are usually rechargeable, there is a finite limit on the amount of time that a portable computing device may be used between charging events.
As a consequence, power consumption is a very important consideration in the design of portable computing devices. Power consumption is also an important operational consideration, and the use of power management utilities and screensavers has become commonplace in laptop computers.